Consider a goldfish bowl with one goldfish. Changes in DO concentration in the bowl are

governed by three processes, $1)$ Do consumption by fish, $2)$ DO consumption for degradation

of BOD in fish excreta, and $3)$ DO mass transfer. Find the steady state BOD and DO

concentration in the fish bowl. Given: water depth $=0\mathrm{.}25m$; Interfacial area $=0\mathrm{.}012m^2$;

Volume $=3L$; DO consumption by fish $=2m\frac{g}{d}$; BOD excretion by fish $=1\mathrm{.}35m\frac{g}{d}$;BOD

degradation rate constant $=\frac{0\mathrm{.}15}{d}$; Saturation DO concentration $=10m\frac{g}{L}$; Interfacial mass

transfer coefficient $=0\mathrm{.}08\frac{m}{d}$